The present invention relates to a bearing support for an impeller shaft in a centrifugal pump. In the related art, as blood pumps which transport blood, there have been known turbo-type pumps which send out blood in response to centrifugal force. The turbo-type pump includes a hollow housing, an impeller that is rotatably accommodated inside the housing, a rotary shaft (i.e., shaft member) that serves as a rotation center of the impeller, an upper bearing that rotatably supports an upper end portion of the rotary shaft, and a lower bearing that rotatably supports a lower end portion of the rotary shaft (see, e.g., Japanese patent 4548450).
In the blood pump disclosed in Japanese patent 4548450, the housing is provided with an inlet port through which blood flows in, and an outlet port through which blood flows out. The inlet port and the outlet port are tubularly formed so as to protrude from the housing. In addition, the inlet port is provided so as to be an extension of the shaft member such that a central axis thereof coincides with the rotational axis of the rotary shaft.
Recently, blood pumps in which the inlet port is provided so as to include an inclined section with respect to the rotary shaft have been adopted. The outer profile of the inclined inlet port intersects an intermediate portion of the shaft member, and the pump housing typically includes a recessed portion or pocket that is coaxially aligned with the shaft member and receives an upper bearing for the shaft member.
However, in such a configuration, due to the depth or the shape of the recessed portion as known in the art, when blood flows down through the inlet port then some blood tends to be retained inside the recessed portion. Therefore, in a case where the blood pump is used for a long time, there is a possibility that a thrombus may be formed inside the recessed portion of the rotary shaft, particularly in an outer peripheral portion of a bearing part which is inserted into the recessed portion of the rotary shaft.